Fashion a piggy bank in the shape of a gas pump. When you deposit money into it, a voice chip responds with a note of praise. Whenever you pull the hose to get money out, another chip answers in the dialect of a west Texas oil baron, "GOTCHA!" It would be great motivation to move toward a fuel-conserving
lifestyle.

They could be made in China for cheap and sold at Wal-Mart... this years big Christmas gift idea.